I guess Mark Zuckerberg likes Alexandr Wang a lot. They have a lot in common. They both value intensity and are willing to engage in morally dubious tactics. The culture of Scale sounded quite a bit like Meta these days (and not Meta in mid 2010s) and may indeed be what Zuckerberg envisioned Meta's culture should be. So even if Scale's product isn't the best, it probably seemed like delegating to a copy of Zuckerberg himself, so it just "felt right".

However, a top research lab needs to be competitive yet still have an environment that fosters intellectual honesty. Meta Gen AI did not seem like that, and I don't think Scale's culture is like that either.